1.Order from sales history feature so customers can view their history and click on items they want to reorder
2.Track order status so customers can check to see when their orders are scheduled to arrive
3. Complete a return form online from their original invoice and have that send a notice to Purolator/Fedex to pick up the item
Thank you

#1 is already standard, simply ogin in as custoemr and cehck the order history
#2 can be achieved by an extension (see marketplace)
#3 guess has to be created new (do not know any extension which can do that)